"It's highly unlikely that any of us three over on my right would have served in the White House or be on this platform had it not been for Martin Luther King Jr. and his movement and his crusade for civil rights," Carter noted as he opened his remarks.
Reince Priebus, chairman of the Republican National Committee, said in a statement that "marchers came to Washington to claim their right to the American Dream, and we can't rest until that dream is in reach for every American."
Thousands marched along Constitution Avenue in the rain, past the Washington Monument and the World War II Memorial. Several wore sashes or carried signs indicating that they had also marched in 1963.
Linda Wills, 59, who attended the first march, said the recent Supreme Court ruling was a major blow to the cause.
"Here we are now 50 years later, and we've been set back," she said. "I'm going to remain a part of the movement until change comes, if the Lord lets me live long enough."
There were also young faces in the crowd, including the eighth-grade class from KIPP Ujima Village Academy in Baltimore.
"We came here to walk in the steps of our ancestors," said 13-year-old Shawn Carroll, who walked alongside 15-year-old Jordan Hopkins. "We came here today to show that we as people should have the same rights as other people."
Colleen Green said she participated Wednesday because she "missed the first one." She was less than 2 years old in 1963. But the Odenton woman was adamant about walking to the Lincoln Memorial on Wednesday.
"It's the right thing to do," she said. "I just felt that I needed to be here."
Sun reporter Michael Dresser and the Tribune Washington bureau contributed to this article.